Method of decarburizing metals or alloys.



UNITED STATES Patented October 4, 1904.

PATENT OFFIcE.

FRANZ VON KIIGELGEN AND GEORGE O. SEIVARD, OF HOLOOMBS ROCK, VIRGINIA,ASSIGNORS TO THE WILLSON ALUMINUM COMPANY, OF NEW YORK, N. Y., ACORPORATION OF NEW YORK.

METHOD OF DECARBURIZING METALS OR ALLOYS:

SPECIFICATION forming part of Letters Patent No. 771,645, dated October4, 1904.

Application filed July 14, 1903. Serial No- 165,5l1. (No specimens.)

To all whom it may concern:

Be it known that we, FRANZ VON KUGELGEN,

a subject of the German Emperor, and GEORGE O. SEWARD, a citizen of theUnited States, re-

siding at Holcombs Rock, in the county of Bedford and State of Virginia,have jointly invented certain new and useful Improvements in the Methodof Decarburizing Metals or Alloys, of which the following is aspecificationi IO In the production of metals and alloys, such as ferrochromium, ferro vanadium,

chromium, vanadium, &c., by electrosmelt-- ing the ores with coke orother carbon it is very diflicult to obtain the metal with a very 5 lowcarbon content. Attempts to keep down the content of carbon by loweringthe quan tity of the reducing agent in the mixture results generally inthe loss of a part of the oxid to be reduced, which is slagged off.

Furthermore, the consumption of the carbon pencils or other electrodesis very large. Often the metal or alloy has to be remelted in order todecarburize it to the desired extent. This of course results in the useof an excessive 5 amount of heat and also an excessive consumption ofcarbon pencils.

According to our process we obtain lowcarbon metals and alloys with agreat economy of heat as compared to the old processes and 3 a smallconsumption of electrodes.

Our process utilizes the great affinity of calcium for carbon. We firstreduce the ores with suflicient carbon to reduce substantially all theoxid without an excessive consumption of the electrodes, and then inorder to bring down the carbon content we bring the metals or alloyswhile still molten into contact with calcium. This may be doneby puttingmetallic calcium in the bottom of the tapping- 4 mold and tapping themetal onto it, or the calcium may be added while the metal is still inthe original furnace, or other ways might be adopted of bringingthemolten metal or alloy into contact with the calcium. The calcium byreason of its great afiinity for carbon forms calcium carbid, whichseparates from the metal while the metal is still molten and which risesto the top and is removed as slag. The affinity of the calcium for thecarbon is so great that no external heat is necessary, 5 (unless it beto keep the metal molten,) heat being generated by their union, in fact,or other ways of getting rid of the calcium carbid may be adopted. Thereis usually a small quantity of oxygen in the metal, and this willoxidize a part of the calcium, leaving only the remainder to unite withthe carbon. It is advisable, therefore, to use an excess of calcium overthat necessary to extract the carbon from the metal, the excess beingpropor- 6O tioned to the oxygen content of the metal.

Our process has the great practical advantage of a high efliciency ofproduction. substantially all the metal being reduced, while at the sametime there is a great saving in 5 electrodes and in the amount of heatused. The first producing of the metal or alloy with a comparativelyhigh content of carbon effects the economies stated, and thesubsequentlowering of the carbon content is unaccompanied 7 by the lossof any of the metal or ore or any other disadvantages incident to priorprocesses. An extremely important advantage is in the fact that certainmetals and alloys can be obtained with a carbon content considerablylower than is possible with prior processes.

Our invention may be modified by using in addition to calcium a suitableproportion of a compound of calcium or other metal to assist? thedecarburizing action of the calcium and to facilitate the separationfrom the resultant metal of the calcium carbid which is formed. Examplesof such compounds are lime,(OaO,) fluor-spar, (Cam) and calcium chlorid(OaOla) 5 Though we have described with great particularity of detailcertain processes embodying our invention, yet it is understood that theinvention is not limited to the specific processes disclosed. Variationsof the same 9 may be made by those skilled in the art without departurefrom the invention.

What we claim is 1. The process of obtaining metals and alloys low incarbon, which consists in bringing a metal which contains an undesirablepercentage of carbon into a molten state in contact with calcium andthereby decarburizing it.

2. The process of obtaining metals or alloys low in carbon, whichconsists in first smelting the ore under such conditions as to secure ahigh output regardless of the amount of car- IO bon in the product, andthen bringing the molten product into contact with calcium and therebydecarburizing it to the desired extent. In witness whereof we havehereunto signed our names in the presence of two subscribing witnesses.

FRANZ VON KUGELGEN. GEO. O. SElVARD. Vitnesses:

O. E. KREBs, T. M. MoRRIsoN.

